ref: ae8a9f8b900f6bd4e0f9c6cd99fbe44c1a46e4a3 dir: /sys/src/libc/amd64/argv0.s/
GLOBL argv0(SB), $8 GLOBL _tos(SB), $8 GLOBL _privates(SB), $8 GLOBL _nprivates(SB), $4